The invention relates to a wood-encased pencil for writing, sketching, drawing and cosmetic purposes. Pencils of this type generally have a wooden jacket accommodating a lead in the center. As used herein, the term xe2x80x9cpencilxe2x80x9d includes pencil-shaped holders for leads, so-called mechanical pencils.
Wood-encased pencils generally have smooth surfaces formed by a coat of paint. Holding the pencil is therefore associated with relatively great application of force, which causes fatigue on extended use. Japanese patent disclosure JP 9-39467 describes a sleeve consisting of plastic or metal which forms the region of a pencil-like applicator that is close to the point and on whose peripheral surface raised structures are present. These consist of a polyurethane resin and are applied to the sleeve surface by screen printing.
It is accordingly an object of the invention to provide a wood-encased pencil for writing, painting, sketching, drawing, and cosmetics application, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which is improved in ergonomic respects.
With the foregoing and other objects in view there is provided, in accordance with the invention, a wood-encased pencil, for example for writing, sketching, drawing, and cosmetic purposes. The pencil comprises:
a pencil body formed with a handling surface; and
raised structures on the handling surface for facilitating holding the pencil body, the raised structures being applied as an initially flowable plastic composition that later solidifies to form the raised structures, and the plastic composition comprising, as principal constituent, an aqueous polymer dispersion, or a mixture of dispersions, that hardens to become water-resistant.
In other words, the objects of the invention are achieved with a pencil whose grip surface has raised structures of a plastic material forming grip surfaces or grip nubs. The structures project from the peripheral surface of the pencil in raised nubs or the like which enable, firstly, the diameter of the pencil to be increased without impairing the ability of the pencil to be sharpened in the standardized sharpening cones of conventional sharpeners. This applies in particular in the case of hexagonal pencils, wherein the raised structures are arranged on the flattened-off surface areas. Secondly, the gripability of the pencil is increased merely through the presence of the raised structures. A further improvement in the gripability and the tactile properties can be achieved by a corresponding plastic material. The raised structures with which at least the front third of the pencil is preferably provided are applied to the pencil surface in the form of an initially flowable plastic composition, the plastic composition subsequently solidifying or being capable of solidification.
The plastic composition is an aqueous polymer dispersion which hardens in a water-resistant manner or a mixture of such dispersions. With respect to adhesive strength, ability to be sharpened, ergonomy and toxicology of the raised structures or plastic composition, particularly good results are obtained with dispersions which comprise a polymer or copolymer from the group consisting of polyurethane, polyacrylate, polystyrene, polyvinyl acetate and polyester-polyurethane. Dispersions or polymers of this type can very generally be solidified by simple drying. However, it is also conceivable for the polymers to contain UV-crosslinkable functional groups. Solidification of the plastic material is then possible in a relatively short time. The viscosity of the initially liquid plastic composition can be adjusted by means of thickeners and also by means of fillers and auxiliaries.
The solids content of the polymer dispersions is preferably in the range from 30 to 65% by weight. By means of dispersions of this type, both the viscosity of the starting plastic composition and also the consistency of the later raised structures can be adjusted through variation of the filler and thickener content. The plastic composition has an uncured starting state which comprises from 30 to 95% by weight of the polymer dispersion and a remainder of fillers and auxiliaries. The plastic composition, in the uncured starting state, comprises in % by weight a polymer dispersion of 40 to 90%, a filler of 0 to 40%, and the remainder being auxiliaries. The fillers used are preferably kaolin talc barium sulfate, titanium white, calcium carbonate and mica. In addition, advantageous fillers are those with which the flexibility, the elasticity, the porosity and the tactile properties of the raised structures can be varied in a targeted manner. Fillers of this type are, in particular, hollow aluminum silicate beads, expanded hollow beads, soft- feel PU beads, micronized plastics, such as polypropylene or PTFE, and PE waxes.
Suitable colorants are, in particular, pigment preparations having pigment contents of from 15 to 75% by weight. The viscosity of the aqueous starting plastic composition, which depends on the desired height of the raised structures and on the type of applicator used, is less than 40000 mpaxc2x7s (250xc2x0C., spindle 64, 25 rpm, Brookfield).
The thickeners used are preferably associative thickeners, such as PU polyethers and, PU polyols. Also possible, however, are non-associative thickeners, those based on acrylate and other thickeners, such as modified bentonites.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a wood-encased pencil for writing, sketching, drawing and cosmetic purposes, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.